The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 18, 2014
Filed:
Aug. 28, 2009
Koichi Kimura, Numazu, JP;
Hiroshi Sawada, Gotenba, JP;
Toru Kidokoro, Hadano, JP;
Yasushi Iwazaki, Ebina, JP;
Koichi Kimura, Numazu, JP;
Hiroshi Sawada, Gotenba, JP;
Toru Kidokoro, Hadano, JP;
Yasushi Iwazaki, Ebina, JP;
Toyota Jidosha Kabushiki Kaisha, Toyota, JP;
Abstract
An air-fuel ratio imbalance among cylinders determining apparatus according to the present invention is applied to a multi-cylinder internal combustion engine in which a compression ratio is variable. The determining apparatus obtains, using at least an output value of an upstream air-fuel ratio sensor disposed for a catalyst, an 'imbalance determining parameter' which becomes larger as a degree of an imbalance among 'individual cylinder air-fuel ratios' becomes larger, each of the individual cylinder air-fuel ratios being an air-fuel ratio of a mixture supplied to each of cylinders. Further, the determining apparatus determines that an air-fuel ratio imbalance state among cylinders is occurring, when the imbalance determining parameter is larger than a predetermined threshold. The determining apparatus changes the predetermined threshold in accordance with a mechanical compression ratio of the engine.